The present invention relates in general to a sub-millimeter wave power distribution device for, and more particularly, to a device using reflective element to obtain a beam shaped as desired to deliver uniform power to a surface.
Millimeter-wave systems offer broad bandwidth and high resolution for radar and imaging applications. Due to the low atmospheric attenuating feature, millimeter waves are ideal for building radars and cameras that can penetrate clouds, smoke, and haze. Systems applications have been limited by the availability of high power sources, which are becoming available. This initiates the need for distributing such high power at millimeter or sub-millimeter wavelengths to an array of detecting or sensing elements.
A variety of techniques have been developed to combine output powers of several power sources, or divide the power of one source. Existing techniques include the resonant approach and the non-resonant approach. In the resonant combining approach, the power sources coherently inject their energies into an eigenmode of a shielded or open resonator. The non-resonant approach is mainly based on spatial combining/dividing of energy. To avoid mode competition in the resonant approach and grating lobes in the non-resonant approach, the sources or receivers are arranged within a space dictated by the wavelength, that is, the distance between neighboring sources and devices is typically equal or less than half a wavelength.
To overcome the above shortcomings and to allow sufficient geometrical spacing, holographic power combining circuit is proposed. For example, Shahabadi et al. proposed a millimeter-wave beam splitter consisting of a hologram and an antenna array published in “Millimeter-Wave Holographic Power Splitting/Combining” in IEEE transactions on Microwave Theory and Techniques, Vol. 45, No. 12, December 1997. Holt et al. proposed a quasi-optical holographic power combining circuit published in “Broadband Analysis of a D-Band Holographic Power Combining Circuit”, IEEE MTT-Symposium, May 2001. In the disclosure of Shahabadi et al., the beam reconstruction is realized within a one-dimensional transmissive structure instead of free space. Holt et al. uses a parallel-plate transmission structure to realize the beam reconstruction. Similar to Shahabadi et al., the signal propagation is limited to one dimension since the one-dimensional array of beam splitter is used.